<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<div class="widget">Hello, world!</div>
		<script>
			var host = document.querySelector('.widget');
			var root = host.createShadowRoot();
			root.textContent = '我在你的 div 里！';
		</script>
	</body>

</html>